Magnetic work-holding device



Jan. 24, D JONYES MAGNETIC WORK HOLDING DEVICE Filed March 30, 1931 5 56 INVENTOR David Jane's ATTO RN EYS Patented Jan. 24, 1933 UNITED STATES DAVID JONES, OF DETBQIT, MICHIGAN EAGNETIG WORK-HOLDING- DEVICE Application fled Iaroh 80, 1831. Serial No. 526,448.

The present invention pertains to a magnetic work-holdin device such as a magnetic jig, or top plateo a magnetic chuck, for use in connection with a magnetic field produced 6 by any suitable means.

' In the building of these devices, considerable difficulty has been encountered in properly fitting t e pole separators into the magnetic material and in maintaining the original sha e of the device after repeated use.

j The 0 ject of this invention therefore, is

t "to overcome these difliculties and is accomplished essentially b utilizing the shrinkage of cooling material 2hr holding the magnetic and non-magnetic parts firmly together. One

of the parts is in the nature of a core or skeleton consisting of suitably shaped pieces held together in spaced and substantially parallel relation. Spacer bars with apertures or protherebetween. Consequently the core pieces a are bound or clamped between the sections of poured material at the opposite surfaces thereof, and a structure is thereby obtained wherein the ole separators cannot possibly become detac ed from the pole pieces.

In constructing a non-magnetic core, a nickel-chromium alloy of80% nickel and 20% chromium, such as nichrome IV may be used, and the magnetic material may be cast steel. The melting point of the core should obviously be high enough to resist the heat of Figs. 7, 8 and 9 are sections on the lines the molten material. The core, however, may consist of magnetic material with spacer bars and binders of non-magnetic material and the enclosing body of non-magnetic material. In such a case, the core may consist of iron and the cast non-magnetic material may be chrome or bronze.

The invention is fully disclosed by way of example in the following description and in the accompanying drawing, in which Figure 1 is a perspective view of a jig constructed according to the invention Fig. 2 is a perspective view of the core or skeleton used therein;

Fig. 3 is a perspective view of one of the 0 tie bars;

Fig. 4 is a construction Fig. 5 is a perspective view of one of the elements thereof;

Fig. 5a is a detail section of a core, showing the loose joint employed in the cores shown in Figs. 2 and 4;

Fig. 6 is a transverse view of a modified construction perspective view of a modified 737, 8-:8 and 99' respectively of Fig. 6, an

Fig. 10 is a perspective view of a modified form of core.

Reference to these views will nowbe made by use of like characters which are employed to designate corresponding parts throughout.

Considering first the right angle jig shown in Figs. 1 and 2, it will be' seen that this de- 0 vice is built around a core formed of a number of strips 1, the sides of which have the configuration and dimensions of the ends of the body to be formed. These members are arranged in parallel relation as shown in Fig. 2 and are thus held by rods 2 passed therethrough. In order to maintain a definite spacing between the members 1 there are 7 provided spacing and connecting bars 3 having notches 4 in one of the edges thereof.

These notches interlock in similar notches 5 formed in the ed of the members 1 and of such depth that t e outer edges of the memhere 4 are flush with the e of the strips 1, as clearly illustrated in 1g. 2. The bars 3 are provided with suitable means, such as apertures 3', for attachment to the material subsequently to be poured into the core.

A magnetic work-holding device comprises a magnetic body divided into separate poles b pieces of non-magnetic'material inserted erein. According to the present invention, the skeleton may consist principally of either metal, and the other metal 6 is poured around the core after placing the core in a mold of proper shape. It is preferred, however, that the skeleton consists of non-magnetic material and that the magnetic material be poured or cast around the same. In either case, the connecting bars or rods should be non-magneticin order to avoid a magnetic connection between ad 'aoent poles.

The note es 4 and 5 are of slightly greater width than the thickness of the metal parts 1 and 3 to be res ectively received therein, so that the joints tween the members 1 and 3 are loose. This loosenes; provides sufficient pla to permit these members to be drawn tot er a shortdistance commensurate with e shrinkage of the cast metal in cooling. In other words, the arts of the core or skeleten are firmly embc dcd or clam d between blocks of cast metal at op osite si es. In this manner the magnetic an non-magnetic partsare bonded together with a firmness comparable with that obtained by machining and fitting. Moreover, the labor necessary for such operations is ,avoided.

In the modification shown in Figs. 4 and 5, the strips or separators are of rectan ular formation with notches 11 in the ed es t ereof. Each such member is forme with an aperture 12, and these apertures are concentric when the members 10 are parallel to each other. Notched spacing bars 13 are inserted in the notches 11 to hold the members 10 loosely joined thereto in parallel relation as described in connection with Figs. 2 and 3. An open ended tube 14, consisting of the same character of metal as the members 10 and 13, is passed loosely through the aligned apertures 12 and held therein. I

The core or skeleton thus formed is placed in an appropriate mold havin approx1mately the shape of the desired ished object, and material of opposite character magnetically is poured therein. The cast metal forms a continuous rod in the tube 14, inteal with and therefore connecting the end locks of solid metal. This rod therefore im roves the firmness and rigidity with which the parts of the device are held together.

The loose joint reviousl mentioned is shown in detail in ig. 5a w ich will be as- Obviously,

, enab sesame sumed to be a cross sectiontaken through one of the spacing bars. The strip or le separator, in the case of a non-magnetic core, is indicated-b the numeral 15 and has a notch 16 in the edge thereof. The spacing bar 17 has a similar notch 18 which receives a portion of the member 15 directl beneath the base of the notch 16. The more rs 15 and 17 are thus interlocked at the notches thereof, and the notch of each member receives the thickness of the other member loosely, as indicated by the numeral 19.

In the modification shown in Figures 6 to 9, each of the ale separating strips 20 has a V- notch 21 in u per edge thereof, so that the jli to be form may be used as a V-block.

e important feature of this construction, however, is that the block may be laid on either of two mutually adjacent sides, so that the V-notch may The means for holding the pole separators 20 in spaced relation prior to pouring the magnetic material consists of tubes 22, 23 and 24: passed therethrough. The cast metal 25 poured around the core forms magnetic blocks at the sides of the pole separators 20.

the device is operative on a magnetic chuck when laid with its bottom face 26 in contact with the usual magnetic top plate, for in this position the poles are separated by the members 20. I

It will be seen by reference to Figs. 7, 8 and 9 that the tubes 22, 23 and 24 are of difierent lengths, extending from one of the faces 27 to succemive poles. When this face is laid on the magnetic top plate, the metal within the tubes forms flux conductors to the successive blocks of metal at the sides of the pole separators. Inasmuch as these blocks are magneticall separated by the members 20 and adap to recelve flux through the metal in the tubes, the device is operative asa magnetic jig when laid on the face 27 Fi 10 shows still another form of core for g the jig to be laid in any position in a given plane upon the top plate as in machinmg or grmdmg angular work. The pole separating strips 30 and 31 are provided at an angle to each other, the members of each series being spaced apart and parallel to each other. The members 30 and 31 may be positloned at an angle to each other because of notches 32 and 33 cut in the ed es thereof so that these arts may be loosefi interlocked in substantlalily the manner described in connection with igs. 2 and 4. Each notch has a depth equal to the width of the unsevered part of the intersectin member, in order to contain the same comp etely, with the result that the members 30 and 31 intersect each other across the entire width thereof to form distinct and separate cells 34. This device is held together by a rod 36 passed through the members 30 and 31. The ma etic metal poured around the core is there ore divided face upwardly or laterally.

metal oi opposite magnetic character, form a magnetic edges. When deemed necessary, the device may he heat treated to improve the megnetic properties and insure retention oi shape.

The expression magnetic character as used herein and in the claims refers to the magnetizehility or non-magnetizahility of the metal rather than to the polarity of magnetized metal.

Although specific embodiments of the invention have been illustrated and descrihed it will he understood that various alterations in the detsils of construction may be made without departing from the scope of the invention as indicated by the appended claims.

What I claim is:

l. A magnetic work-holding device comprising e plurality of spaced members meens loosely connecting said spaced memlrers, cast material having a positive co-eiiticient of expansion and of opposite ma etic charac ter enclosing said members an leaving oer tain edges thereof exposed at the surfaces of said material.

2., A magnetic work-holding device com prising a plurality oi? spaced memloers, spacing hers having a loose nt with said members, a cast meterial having a positive co-eficient oi expansion and of opposite magnetic char acter enclosin said members and leaving certain edges thereot exposed at the surfaces or said material,

3.. A magnetic work-holding device comprising a plurality of spaced members, an open-ended element passing through said members, and cast material havin tive co-eficient of expansion and o opposite magnetic character enclosing said members an filling said element while leaving certain edges of said members exposed at'the surfaces of said material.

4. A magnetic work-holding device comprising two series of spaced members of equal width intersectin each other, the intersections being provi ed by means of loose notch joints bringing the intersecting edges of one series into t e same planes as t edges of the other series, and material of opposite magnetic character at' the sides of the members, filling the spaces therebetween and leaving said intersecting edges exposed at the surfaces of said material,

1 5. A work-holding device comprising a plurality of pole separators ins acedand substantially parallel relation, tu es of difa posie intersecting ferent len s passed through said so a.-

rators, sa-i tubes having one end dispose in a common plane and the remaining ends disposed in successive spaces between said separators, and magnetic material at the sides of said separators, filling the spaces therebetween and said tuhes, while leaving the first named ends and the edges of said separators ex osed at the surfaces of said materml.

in testimony whereof I a my si etnre,

DAWD JO ES.

Hill

Mitt

lid 

